In 2006, a Utah woman named Anndorie Sachs received a phone call that no mother ever wants to hear. She was being investigated by Child Protective Services after recently giving birth to a baby who was addicted to meth. Investigators actually arrived at her house, threatening to take her four children into custody.

There were several problems with the situation, the first being that Sachs hadn’t given birth in years. But despite showing the investigators her healthy, older children, the threat was held over her head for quite some time. While nowhere near as upsetting as the possibility of losing your children when you’ve done nothing wrong, Sachs also learned she was responsible for a $10,000 medical bill for the recent birth.

How did this nightmare happen? Someone who was addicted to methamphetamine had stolen Sachs’ driver’s license prior to her child’s birth and used the stolen identity at the time of delivery. She left the hospital without paying the bill, and without taking responsibility for any of the crimes she’d committed.

Once the issue was resolved for Sachs, the real danger began. Due to HIPAA privacy laws, medical records and treatments are kept private, even from the person whose identity had been claimed. Sachs had no right to see the other woman’s records, and no way to alter those records even though her name was on them.

If the birth mother had a different blood type, for example, or had a heart condition, those factors could end up being deadly for Sachs the next time she needed medical care. Of course, her records also now stated she was a meth addict, another factor that she couldn’t change.

You don’t have to wait for investigators to show up on your doorstep to know you’ve been a victim of medical identity theft. There are a few tell-tale signs that your medical information may have been compromised:

If you receive bills or health insurance statements for treatments that you never received, from doctors you’ve never heard of, or in cities that you haven’t been to, someone may be using your identity; it’s important that you don’t dismiss these as a billing error or computer glitch, but instead that you take immediate action to undo the damage.

If you’re denied a course of treatment like a specific antibiotic because of a stated allergy in your records, or if your doctor tells you he cannot mandate a certain treatment because it conflicts with a condition you don’t actually have, there may be information in your medical records that doesn’t actually pertain to you.

Of course, medical identity theft can have crossover potential for criminal identity theft, as in Sachs’ case. It could also be indications of other red flag triggers, like large quantities of prescription pain medicines or pseudoephedrine, a key ingredient in the manufacture of crystal meth; if you’re approached by law enforcement over prescriptions that you know nothing about, the first place to look is in your medical records.

Finally, keep in mind that someone out there has enough of your identifying information to seek medical treatment in your name. If they’ll go that far, there’s nothing stopping them from opening new lines of credit, applying for loans or even employment, or renting a house. Make sure you watch all aspects of your identity carefully once you discover a crime has occurred.

Whatever the warning sign, it’s important that you take medical identity theft seriously. It’s both hopeful and downright frightening that the number of cases of medical identity theft have risen sharply in the past few years. On the one hand, investigators are now more aware of the crime and better equipped to deal with it, but at the same time, it means the number of criminals perpetrating this type of identity theft has reached such proportions that individuals have serious cause for alarm. Of all the types of identity theft, this one can have deadly consequences for the victim, which is why prevention and swift response are absolutely crucial.